Degree Type


Date of Award


Degree Name

Doctor of Philosophy



First Advisor

Gary L. Wells


Eyewitnesses are often asked in real-world cases whether their responses to a lineup were affected by various external influences, but their ability to answer these types of questions accurately is unknown. Two experiments used a new paradigm to examine eyewitnesses' abilities to estimate the influence of lineup manipulations. Eyewitnesses were administered either confirming post-identification feedback or no post-identification feedback (Experiment 1, n = 103), or a cautionary pre-lineup instruction or no cautionary pre-lineup instruction (Experiment 2, n = 114). Eyewitnesses then gave actual responses (retrospective confidence, view, and attention measures in Experiment 1; identification decision in Experiment 2) as well as counterfactual responses stating how they would have responded in the alternative condition. Results across both studies showed an asymmetric estimation of influence pattern: Eyewitnesses who received an influencing manipulation estimated significantly less of a change in their responses than eyewitnesses who did not receive an influencing manipulation. In Experiment 1, eyewitnesses who received confirming feedback accurately estimated the influence of feedback whereas eyewitnesses who did not receive feedback overestimated the influence of feedback. In Experiment 2, eyewitnesses who received a cautionary pre-lineup instruction underestimated the 2 influence of the instruction whereas eyewitnesses who did not receive the cautionary instruction accurately estimated its influence. The observed asymmetric estimation of influence pattern is consistent with research on the hindsight bias as well as research on counterfactual thinking. Variations in the asymmetric estimation of influence pattern might be explained by the different implicit theories witnesses have about the influence of various lineup manipulations. A 48-hr delay between actual and counterfactual responses was not shown to moderate any effects.



Digital Repository @ Iowa State University,

Copyright Owner

Steve Douglas Charman



Proquest ID


File Format


File Size

94 pages